Current management of newly diagnosed acute promyelocytic leukemia

Autophagy Inhibition-induced Cytosolic DNA Sensing Combined with Differentiation Therapy Induces Irreversible Myeloid Differentiation in Leukemia Cells

Accumulating evidence indicates that various oncogenic mutations interfere with normal myeloid differentiation of leukemogenic cells during the early process of acute myeloid leukemia (AML) development. Differentiation therapy is a therapeutic strategy capable of terminating leukemic expansion by reactivating the differentiation potential; however, the plasticity and instability of leukemia cells counteract the establishment of treatments aimed at irreversibly inducing and maintaining their differentiation states. On the basis of our previous observation that autophagy inhibitor treatment induces the accumulation of cytosolic DNA and activation of cytosolic DNA-sensor signaling selectively in leukemia cells, we herein examined the synergistic effect of cytosolic DNA-sensor signaling activation with conventional differentiation therapy on AML. The combined treatment succeeded in inducing irreversible differentiation in AML cell lines. Mechanistically, cytosolic DNA was sensed by absent in melanoma 2 (AIM2), a cytosolic DNA sensor. Activation of the AIM2 inflammasome resulted in the accumulation of p21 through the inhibition of its proteasomal degradation, thereby facilitating the myeloid differentiation. Importantly, the combined therapy dramatically reduced the total leukemia cell counts and proportion of blast cells in the spleens of AML mice. Collectively, these findings indicate that the autophagy inhibition-cytosolic DNA-sensor signaling axis can potentiate AML differentiation therapy.

SIGNIFICANCE

Clinical effects on AML therapy are closely associated with reactivating the normal myeloid differentiation potential in leukemia cells. This study shows that autophagosome formation inhibitors activate the cytosolic DNA-sensor signaling, thereby augmenting conventional differentiation therapy to induce irreversible differentiation and cell growth arrest in several types of AML cell lines.

Risk stratification for early mortality in newly diagnosed acute promyelocytic leukemia: a multicenter, non-selected, retrospective cohort study

Introduction

Despite the current effective treatments for acute promyelocytic leukemia (APL), early mortality (EM), defined as death within 30 days of presentation, is a major hurdle to long-term survival.

Methods

We performed a multicenter retrospective study to evaluate the incidence and clinical characteristics of EM in patients with newly diagnosed APL and to develop a risk stratification model to predict EM.

Results

We identified 313 eligible patients diagnosed between 2000 and 2021 from five academic hospitals. The median age was 50 years (range 19-94), and 250 (79.9%) patients were <65 years. Most patients (n=274, 87.5%) received their first dose of all-trans retinoic acid (ATRA) within 24 hours of presentation. EM occurred in 41 patients, with a cumulative incidence of 13.1%. The most common cause of EM was intracranial hemorrhage (n=22, 53.6%), and most EMs (31/41, 75.6%) occurred within the first seven days of APL presentation. In a multivariable analysis, we identified three independent factors predicting EM: age ≥65 years (HR, 2.56), white blood cell count ≥8.0 x 109/L (HR, 3.30), and ATRA administration >24 hours of presentation (HR, 2.95). Based on these factors, patients were stratified into three categories with a significantly increasing risk of EM: 4.1% for low risk (54.3%; no risk factors; HR 1), 18.5% for intermediate risk (34.5%; 1 factor; HR 4.81), and 40.5% for high risk (11.2%; 2-3 factors; HR 13.16).

Discussion

The risk of EM is still not negligible in this era of ATRA-based therapies. Our risk model serves as a clinically useful tool to identify high-risk patients for EM who may be candidates for novel treatments and aggressive supportive strategies.

Developmental basis of SHH medulloblastoma heterogeneity

Many genes that drive normal cellular development also contribute to oncogenesis. Medulloblastoma (MB) tumors likely arise from neuronal progenitors in the cerebellum, and we hypothesized that the heterogeneity observed in MBs with sonic hedgehog (SHH) activation could be due to differences in developmental pathways. To investigate this question, here we perform single-nucleus RNA sequencing on highly differentiated SHH MBs with extensively nodular histology and observed malignant cells resembling each stage of canonical granule neuron development. Through innovative computational approaches, we connect these results to published datasets and find that some established molecular subtypes of SHH MB appear arrested at different developmental stages. Additionally, using multiplexed proteomic imaging and MALDI imaging mass spectrometry, we identify distinct histological and metabolic profiles for highly differentiated tumors. Our approaches are applicable to understanding the interplay between heterogeneity and differentiation in other cancers and can provide important insights for the design of targeted therapies.

Vitamin C enhances the sensitivity of osteosarcoma to arsenic trioxide via inhibiting aerobic glycolysis

Osteosarcoma (OS) is a common malignant tumor disease in the department of orthopedics, which is prone to the age of adolescents and children under 20 years old. Arsenic trioxide (ATO), an ancient poison, has been reported to play a critical role in a variety of tumor treatments, including OS. However, due to certain poisonous side effects such as cardiotoxicity and hepatotoxicity, clinical application of ATO has been greatly limited. Here we report that low doses of ATO (1 μM) observably reduced the half-effective inhibitory concentration (IC50) of vitamin C on OS cells. Compared with the treatment alone, the synthetic application of vitamin C (VitC, 800 μM) and ATO (1 μM) significantly further inhibited the proliferation, migration, and invasion of OS cells and promoted cell apoptosis in vitro. Meanwhile, we observed that the combined application of VitC and ATO directly suppresses the aerobic glycolysis of OS cells with the decreased production of pyruvate, lactate, and ATP via inhibiting the expression of the critical glycolytic genes (PGK1, PGM1, and LDHA). Moreover, the combination of VitC (200 mg/kg) and ATO (1 mg/kg) with tail vein injection significantly delayed OS growth and migration of nude mice by inhibiting aerobic glycolysis of OS. Thus, our results demonstrate that VitC effectively increases the sensitivity of OS to low concentrations of ATO via inhibiting aerobic glycolysis to alleviate the toxic side effects of high doses of arsenic trioxide, suggesting that synthetic application of VitC and ATO is a promising approach for the clinical treatment of human OS.

PARP-1 improves leukemia outcomes by inducing parthanatos during chemotherapy

Previous chemotherapy research has focused almost exclusively on apoptosis. Here, a standard frontline drug combination of cytarabine and idarubicin induces distinct features of caspase-independent, poly(ADP-ribose) polymerase 1 (PARP-1)-mediated programmed cell death "parthanatos" in acute myeloid leukemia (AML) cell lines (n = 3/10 tested), peripheral blood mononuclear cells from healthy human donors (n = 10/10 tested), and primary cell samples from patients with AML (n = 18/39 tested, French-American-British subtypes M4 and M5). A 3-fold improvement in survival rates is observed in the parthanatos-positive versus -negative patient groups (hazard ratio [HR] = 0.28-0.37, p = 0.002-0.046). Manipulation of PARP-1 activity in parthanatos-competent cells reveals higher drug sensitivity in cells that have basal PARP-1 levels as compared with those subjected to PARP-1 overexpression or suppression. The same trends are observed in RNA expression databases and support the conclusion that PARP-1 can have optimal levels for favorable chemotherapeutic responses.

Hedgehog signaling in tissue homeostasis, cancers, and targeted therapies

The past decade has seen significant advances in our understanding of Hedgehog (HH) signaling pathway in various biological events. HH signaling pathway exerts its biological effects through a complex signaling cascade involved with primary cilium. HH signaling pathway has important functions in embryonic development and tissue homeostasis. It plays a central role in the regulation of the proliferation and differentiation of adult stem cells. Importantly, it has become increasingly clear that HH signaling pathway is associated with increased cancer prevalence, malignant progression, poor prognosis and even increased mortality. Understanding the integrative nature of HH signaling pathway has opened up the potential for new therapeutic targets for cancer. A variety of drugs have been developed, including small molecule inhibitors, natural compounds, and long non-coding RNA (LncRNA), some of which are approved for clinical use. This review outlines recent discoveries of HH signaling in tissue homeostasis and cancer and discusses how these advances are paving the way for the development of new biologically based therapies for cancer. Furthermore, we address status quo and limitations of targeted therapies of HH signaling pathway. Insights from this review will help readers understand the function of HH signaling in homeostasis and cancer, as well as opportunities and challenges of therapeutic targets for cancer.

Current and Emerging Techniques for Diagnosis and MRD Detection in AML: A Comprehensive Narrative Review

Acute myeloid leukemia (AML) comprises a group of hematologic neoplasms characterized by abnormal differentiation and proliferation of myeloid progenitor cells. AML is associated with poor outcome due to the lack of efficient therapies and early diagnostic tools. The current gold standard diagnostic tools are based on bone marrow biopsy. These biopsies, apart from being very invasive, painful, and costly, have low sensitivity. Despite the progress uncovering the molecular pathogenesis of AML, the development of novel detection strategies is still poorly explored. This is particularly important for patients that check the criteria for complete remission after treatment, since they can relapse through the persistence of some leukemic stem cells. This condition, recently named as measurable residual disease (MRD), has severe consequences for disease progression. Hence, an early and accurate diagnosis of MRD would allow an appropriate therapy to be tailored, improving a patient's prognosis. Many novel techniques with high potential in disease prevention and early detection are being explored. Among them, microfluidics has flourished in recent years due to its ability at processing complex samples as well as its demonstrated capacity to isolate rare cells from biological fluids. In parallel, surface-enhanced Raman scattering (SERS) spectroscopy has shown outstanding sensitivity and capability for multiplex quantitative detection of disease biomarkers. Together, these technologies can allow early and cost-effective disease detection as well as contribute to monitoring the efficiency of treatments. In this review, we aim to provide a comprehensive overview of AML disease, the conventional techniques currently used for its diagnosis, classification (recently updated in September 2022), and treatment selection, and we also aim to present how novel technologies can be applied to improve the detection and monitoring of MRD.

Measurable Residual Disease (MRD) as a Surrogate Efficacy-Response Biomarker in AML

In acute myeloid leukemia (AML) many patients experience relapse, despite the achievement of morphological complete remission; therefore, conventional morphologic criteria are currently considered inadequate for assessing the quality of the response after treatment. Quantification of measurable residual disease (MRD) has been established as a strong prognostic marker in AML and patients that test MRD negative have lower relapse rates and better survival than those who test positive. Different techniques, varying in their sensitivity and applicability to patients, are available for the measurement of MRD and their use as a guide for selecting the most optimal post-remission therapy is an area of active investigation. Although still controversial, MRD prognostic value promises to support drug development serving as a surrogate biomarker, potentially useful for accelerating the regulatory approval of new agents. In this review, we will critically examine the methods used to detect MRD and its potential role as a study endpoint.

Improvement of Early Death in Acute Promyelocytic Leukemia: A Population-Based Analysis

BACKGROUND

Early death is a major factor of treatment failure in acute promyelocytic leukemia (APL), however, the recent trends in the incidence of early death based on the population-level are not clear. Hence, this study is aimed at describing the incidence, recent trends, causes and characteristics of early death in APL based on the real world.

MATERIALS AND METHODS

APL patients diagnosed from 1986 to 2015 in the Surveillance, Epidemiology, and End Results (SEER) dataset were enrolled, and categorized based on gender, age, year of diagnosis, race, marital status, resident county and socioeconomic status (SES). The risk factors for all-cause and acute myelocytic leukemia (AML) specific early death were determined by univariate and multivariate logistic regression analyses, and stratified analysis was conducted by age.

RESULTS

Overall, 3212 APL patients were included in analysis between 1986 and 2015, of which a total of 683 (21.3%) patients were noted for early death. Significant differences were recognized for patient distribution by age, year of diagnosis, marital status, and SES. The early death rate of APL patients diagnosed during 2006-2015 was significantly lower than that of the early stage, but this trend was not evident in juvenile patients. At the same time, older age, and lower SES score were independent risk factors for early death in the multivariate analysis.

CONCLUSION

We established that the early death trend in APL has decreased over the past few years, but the early death rate remains high, especially in older patients and those with lower SES.

At What Point Are Long-Term (>5 Years) Survivors of APL Safe? A Study from the SEER Database

BACKGROUND

Acute promyelocytic leukemia (APL) is a highly curable cancer, but it is not clear whether it is also necessary to monitor long-term toxicity in "cured" patients who survive for more than five years, which is critical to ensuring maximum survival in APL patients.

METHODS

A total of 1952 APL 5-year survivors and 5973 non-APL acute myeloid leukemia (AML) 5-year survivors were included from the Surveillance, Epidemiology, and End Results (SEER) database. The standardized mortality ratio (SMR) was calculated to measure the risk of death. Cumulative mortality is calculated as the incidence of specific causes of death under competing risk events.

RESULTS

The SMR of all causes of death in >5-year survivors of APL was higher than that of the general population only at 60-119 months (SMR, 1.41). This was mainly because a significant increase in mortality from AML (SMR, 87.67) and second malignant neoplasms (SMNs) (SMR, 1.56) was found only at 60-119 months. However, there was no higher risk of death from non-cancer-related disease in >5-year survivors of APL than that of the general population (SMR, 0.89). The SMR of all-cause deaths in >5-year survivors of non-APL AML decreased year by year and was no higher than that of the general population until after 216 months. The cumulative incidence of AML-related death, SMN-related death, and non-cancer-related death was significantly lower in APL patients than in non-APL AML patients throughout the follow-up period.

CONCLUSIONS

Compared with the general population, the risk of death of patients with APL was higher within 5 to 10 years but not higher over 10 years. Therefore, we believe that long-term survivors of APL are safe after 10 years.

The mythological chimera and new era of relapse prediction post-transplant

Allogeneic hemopoietic stem cell transplantation is the treatment of choice for high-risk or relapsed acute leukemia. However, unfortunately, relapse post-transplant continues to be the most common cause of treatment failure with 20-80% of patients relapsing based on disease risk and status at transplant. Advances in molecular profiling of different hematological malignancies have enabled us to monitor low level disease before and after transplant and develop a more personalized approach to the management of these disease including early detection post-transplant. While, in general, detectable disease by morphology remains the gold standard to diagnosing relapse, multiple approaches have allowed detection of cancer cells earlier, using peripheral blood-based methods with sensitivities as high as 1:10⁶, together called minimal/measurable residual disease (MRD) detection. However, a in significant number of patients with acute leukemia where no such molecular markers exist it remains challenging to detect early relapse. In such patients who receive transplantation, chimerism monitoring remains the only option. An increase in mixed chimerism in post allogeneic HCT patients has been correlated with relapse in multiple studies. However, chimerism monitoring, while commonly accepted as a tool for assessing engraftment, has not been routinely used for relapse detection, at least in part because of the lack of standardized, high sensitivity, reliable methods for chimerism detection. In this paper, we review the various methods employed for MRD and chimerism detection post-transplant and discuss future trends in MRD and chimerism monitoring from the viewpoint of the practicing transplant physician.

The recognition of oral manifestations of haematological disease saves lives: a case report

BACKGROUND

Acute Leukaemias are haematological disorders characterised by the proliferation of immature white blood cells in the bone marrow and/or peripheral blood. Oral manifestations of leukaemia are common and may be the first sign of the disease. The clinical presentation of these Acute Leukaemias may include neutropenic sepsis, hyperviscocity and coagulopathy which confer a potential morbidity and mortality. Clinicians must be able to recognise this pattern of presentation.

CASE REPORT

We report a 34-year-old female who was referred to the Oral and Maxillofacial Surgery department with acute dental pain and pericoronitis. She subsequently had a simple dental extraction but re-presented with a bleeding socket that did not respond to local treatment. Investigation of this led to a diagnosis of Acute Promyelocytic Leukemia (APL). She was admitted under the care of the haematology team for urgent, life-saving, treatment.

CONCLUSIONS

Early diagnosis and treatment of the Acute Leukaemias can be life saving. The oral manifestations of disease are common and may be the first sign. Clinicians must be able to recognise this pattern of presentation and arrange urgent investigation and specialist management.

CLINICAL/CPD RELEVANCE

This case report discusses leukaemia and highlights the important role General Dental Practitioners can play in early diagnosis. We frame a safe approach to managing these patients in a typical case. Whilst this disease subtype is rare, the learning points can be universally applied.

Long-term follow-up results of cytarabine-containing chemotherapy for acute promyelocytic leukemia

BACKGROUND/AIMS

We evaluated the feasibility and long-term efficacy of the combination of cytarabine, idarubicin, and all-trans retinoic acid (ATRA) for treating patients with newly diagnosed acute promyelocytic leukemia (APL).

METHODS

We included 87 patients with newly diagnosed acute myeloid leukemia and a t(15;17) or promyelocytic leukemia/retinoic acid receptor alpha (PML-RARα) mutation. Patients received 12 mg/m2/day idarubicin intravenously for 3 days and 100 mg/m2/day cytarabine for 7 days, plus 45 mg/m2/day ATRA. Clinical outcomes included complete remission (CR), relapse-free survival (RFS), overall survival (OS), and the secondary malignancy incidence during a 20-year follow-up.

RESULTS

The CR, 10-year RFS, and 10-year OS rates were 89.7%, 94.1%, and 73.8%, respectively, for all patients. The 10-year OS rate was 100% for patients that achieved CR. Subjects were classified according to the white blood cell (WBC) count in peripheral blood at diagnosis (low-risk, WBC < 10,000/mm3; high-risk, WBC ≥ 10,000/mm3). The low-risk group had significantly higher RFS and OS rates than the high-risk group, but the outcomes were not superior to the current standard treatment (arsenic trioxide plus ATRA). Toxicities were similar to those observed with anthracycline plus ATRA, and higher than those observed with arsenic trioxide plus ATRA. The secondary malignancy incidence after APL treatment was 2.7%, among the 75 patients that achieved CR, and 5.0% among the 40 patients that survived more than 5 years after the APL diagnosis.

CONCLUSION

Adding cytarabine to anthracycline plus ATRA was not inferior to anthracycline plus ATRA alone, but it was not comparable to arsenic trioxide plus ATRA. The probability of secondary malignancy was low.

Vitamin C Deficiency in Patients With Acute Myeloid Leukemia

Vitamin C has been shown to play a significant role in suppressing progression of leukemia through epigenetic mechanisms. We aimed to study the role of vitamin C in acute myeloid leukemia (AML) biology and clinical course. To this purpose, the plasma levels of vitamin C at diagnosis in 62 patients with AML (including 5 cases with acute promyelocytic leukemia, APL),7 with myelodysplastic syndrome (MDS), and in 15 healthy donors (HDs) were studied. As controls, vitamins A and E levels were analysed. Expression of the main vitamin C transporters and of the TET2 enzyme were investigated by a specific RQ-PCR while cytoplasmic vitamin C concentration and its uptake were studied in mononuclear cells (MNCs), lymphocytes and blast cells purified from AML samples, and MNCs isolated from HDs. There were no significant differences in vitamin A and E serum levels between patients and HDs. Conversely, vitamin C concentration was significantly lower in AML as compared to HDs (p&lt;0.0001), inversely correlated with peripheral blast‐counts (p=0.029), significantly increased at the time of complete remission (CR) (p=0.04) and further decreased in resistant disease (p=0.002). Expression of the main vitamin C transporters SLC23A2, SLC2A1 and SLC2A3 was also significantly reduced in AML compared to HDs. In this line, cytoplasmic vitamin C levels were also significantly lower in AML-MNCs versus HDs, and in sorted blasts compared to normal lymphocytes in individual patients. No association was found between vitamin C plasma levels and the mutation profile of AML patients, as well as when considering cytogenetics or 2017 ELN risk stratification groups. Finally, vitamin C levels did not play a predictive role for overall or relapse-free survival. In conclusion, our study shows that vitamin C levels are significantly decreased in patients with AML at the time of initial diagnosis, further decrease during disease progression and return to normal upon achievement of CR. Correspondingly, low intracellular levels may mirror increased vitamin C metabolic consumption in proliferating AML cells.

Case Report: Extramedullary Acute Promyelocytic Leukemia: An Unusual Case and Mini-Review of the Literature

Background

Acute promyelocytic leukemia (APL) constitutes a serious hematological emergency necessitating rapid diagnosis and therapy to prevent lethal bleedings resulting from APL-induced thrombocytopenia and coagulopathy. Atypical manifestations of APL, such as extramedullary disease at first presentation, pose diagnostic challenges and delay the onset of appropriate therapy. Nevertheless, extramedullary manifestations of APL are mostly accompanied by blood count alterations pointing to an underlying hematological disease. In this report, we present the first case of APL bearing close resemblance to a metastasized laryngeal carcinoma with normal blood counts and absent coagulopathy.

Case Presentation

A 67-year-old man with a previous history of smoking was admitted to our hospital with progressive hoarseness of voice, odynophagia, dysphagia and exertional dyspnea. Laryngoscopy revealed a fixed right hemi larynx with an immobile right vocal fold. Imaging of the neck via magnetic-resonance imaging (MRI) and positron emission tomography–computed tomography (PET/CT) with F-18-fluordeoxyglucose (FDG) showed a large hypermetabolic tumor in the right piriform sinus and tracer uptake in adjacent lymph nodes, highly suspicious of metastasized laryngeal carcinoma. Surprisingly the histological examination revealed an extramedullary manifestation of acute promyelocytic leukemia. Remarkably, blood counts and coagulation parameters were normal. Moreover, no clinical signs of hemorrhage were found. PML-RARA fusion was detected in both laryngeal mass and bone marrow. After diagnosis of APL, ATRA-based chemotherapy was initiated resulting in complete remission of all APL manifestations.

Conclusions

This is the first case report of APL initially presenting as laryngeal chloroma. Additionally, we performed a comprehensive literature review of previously published extramedullary APL manifestations. In aggregate, a normal blood count at first presentation constitutes an extremely rare finding in patients initially presenting with extramedullary APL manifestations.

Current Advances of Nanomedicines Delivering Arsenic Trioxide for Enhanced Tumor Therapy

Arsenic trioxide (ATO) is one of the first-line chemotherapeutic drugs for acute promyelocytic leukemia. Its anti-cancer activities against various human neoplastic diseases have been extensively studied. However, the clinical use of ATO for solid tumors is limited, and these limitations are because of severe systemic toxicity, low bioavailability, and quick renal elimination before it reaches the target site. Although without much success, several efforts have been made to boost ATO bioavailability toward solid tumors without raising its dose. It has been found that nanomedicines have various advantages for drug delivery, including increased bioavailability, effectiveness, dose-response, targeting capabilities, and safety as compared to traditional drugs. Therefore, nanotechnology to deliver ATO to solid tumors is the main topic of this review, which outlines the previous and present medical applications of ATO. We also summarised ATO anti-cancer mechanisms, limitations, and outcomes of combinatorial treatment with chemo agents. As a result, we strongly recommend conducting pre-clinical and clinical studies of ATO, especially nano-system-based ones that might lead to a novel combination therapy for cancer treatment with high efficacy, bioavailability, and low toxicity for cancer patients.

Glutathione protects against the meiotic defects of ovine oocytes induced by arsenic exposure via the inhibition of mitochondrial dysfunctions

Accumulating evidences revealed the connections between arsenic exposure and mitochondrial dysfunctions induced reproductive toxicology. Meanwhile, production declines were found in livestock suffering from arsenic exposure. However, the connections between arsenic exposure and livestock meiotic defects remain unclear. In this study, the effects of sodium arsenite (NaAsO2) exposure during the in vitro maturation (IVM) on the meiotic potentials of ovine oocytes were analyzed. Furthermore, the effects of glutathione (GSH) supplementation on the meiotic defects of NaAsO2 exposed ovine oocytes were investigated by the assay of nuclear maturation, spindle organization, chromosome alignment, cytoskeleton assembly, cortical granule (CGs) dynamics, mitochondrial dysfunctions, reactive oxygen species (ROS) accumulation, oxidative DNA damages, cellular apoptosis, epigenetic modifications and fertilization capacities. The results showed that the meiotic defects of NaAsO2 exposed ovine oocytes were effectively ameliorated by the GSH supplementation via the inhibition of mitochondrial dysfunctions, which not only promoted the nuclear maturation, spindle organization, chromosome alignment, cytoskeleton assembly, CGs dynamic and fertilization capacities, but also inhibited the ROS accumulation, oxidative DNA damages and apoptosis of ovine MII oocytes. The abnormal expressions of 5mC, H3K4me3 and H3K9me3 in NaAsO2 exposed ovine oocytes, indicating the abnormal epimutations of DNA methylation and histone methylation, were also effectively ameliorated by the GSH supplementation. Taken together, this study confirmed the connections between arsenic exposure and meiotic defects of ovine oocytes. Meanwhile, the effects of GSH supplementation on the developmental competence of livestock oocytes, especially for these suffering from arsenic exposure were also founded, benefiting the extended researches for the GSH applications.

Optimizing autologous hematopoietic stem cell transplantation for acute leukemia

Autologous hematopoietic stem cell transplantation (ASCT) remains an important postremission treatment for acute leukemia (AL). It is known that some prognostic factors, such as age, cytogenetic and molecular risk stratification, and minimal residual disease (MRD) status, are closely related to clinical outcomes following ASCT. Moreover, there are multiple measurements, including pretransplant treatment, stem cell mobilization and collection, conditioning regimens, and maintenance treatment after transplantation, that can affect prognosis after ASCT. Our clinical practice of ASCT should be better standardized to further improve patient outcomes. This review outlines optimization and quality control measures for ASCT developed at the Institute of Hematology and Blood Diseases Hospital of the Chinese Academy of Medical Sciences, the first established and largest autologous stem cell transplant center in China. These measures will enhance the development of best practices and strategies for AL ASCT therapies, thereby improving patient outcomes.

Arsenic Combined With All-Trans Retinoic Acid for Pediatric Acute Promyelocytic Leukemia: Report From the CCLG-APL2016 Protocol Study

PURPOSE

Arsenic combined with all-trans retinoic acid (ATRA) is the standard of care for adult acute promyelocytic leukemia (APL). However, the safety and effectiveness of this treatment in pediatric patients with APL have not been reported on the basis of larger sample sizes.

METHODS

We conducted a multicenter trial at 38 hospitals in China. Patients with newly diagnosed APL were stratified into two risk groups according to baseline WBC count and FLT3-ITD mutation. ATRA plus arsenic trioxide or oral arsenic without chemotherapy were administered to the standard-risk group, whereas ATRA, arsenic trioxide, or oral arsenic plus reduced-dose anthracycline were administered to the high-risk group. Primary end points were event-free survival and overall survival at 2 years.

RESULTS

We enrolled 193 patients with APL. After a median follow-up of 28.9 months, the 2-year overall survival rate was 99% (95% CI, 97 to 100) in the standard-risk group and 95% (95% CI, 90 to 100) in the high-risk group (P = .088). The 2-year event-free survival was 97% (95% CI, 93 to 100) in the standard-risk group and 90% (95% CI, 83 to 96) in the high-risk group (P = .252). The plasma levels of arsenic were significantly elevated after treatment, with a stable effective level ranging from 42.9 to 63.2 ng/mL during treatment. In addition, plasma, urine, hair, and nail arsenic levels rapidly decreased to normal 6 months after the end of treatment.

CONCLUSION

Arsenic combined with ATRA is effective and safe in pediatric patients with APL, although long-term follow-up is still needed.

Targeting steroid hormone receptors for anti-cancer therapy-A review on small molecules and nanotherapeutic approaches

The steroid hormone receptors (SHRs) among nuclear hormone receptors (NHRs) are steroid ligand-dependent transcription factors that play important roles in the regulation of transcription of genes promoted via hormone responsive elements in our genome. Aberrant expression patterns and context-specific regulation of these receptors in cancer, have been routinely reported by multiple research groups. These gave an window of opportunity to target those receptors in the context of developing novel, targeted anticancer therapeutics. Besides the development of a plethora of SHR-targeting synthetic ligands and the availability of their natural, hormonal ligands, development of many SHR-targeted, anticancer nano-delivery systems and theranostics, especially based on small molecules, have been reported. It is intriguing to realize that these cytoplasmic receptors have become a hot target for cancer selective delivery. This is in spite of the fact that these receptors do not fall in the category of conventional, targetable cell surface bound or transmembrane receptors that enjoy over-expression status. Glucocorticoid receptor (GR) is one such exciting SHR that in spite of it being expressed ubiquitously in all cells, we discovered it to behave differently in cancer cells, thus making it a truly druggable target for treating cancer. This review selectively accumulates the knowledge generated in the field of SHR-targeting as a major focus for cancer treatment with various anticancer small molecules and nanotherapeutics on progesterone receptor, mineralocorticoid receptor, and androgen receptor while selectively emphasizing on GR and estrogen receptor. This review also briefly highlights lipid-modification strategy to convert ligands into SHR-targeted cancer nanotherapeutics. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Lipid-Based Structures Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Drug treatment options for acute promyelocytic leukemia

INTRODUCTION

Until the late 1980s, acute promyelocytic leukemia (APL) was the most rapidly fatal leukemia; however, nowadays, it is a curable disease with survival rates exceeding 90-95%. The improvement of APL outcome is mainly due to two agents, which target the typical translocation t(15;17) and its fusion transcript PML-RARα responsible for initiating and maintaining the disease: all-trans retinoic acid (ATRA) and arsenic trioxide (ATO). The story of APL represents a pioneering model for the development of precision medicine and curative chemotherapy-free approaches for acute leukemia.

AREA COVERED

The authors examine the major advances in the treatment of patients with APL focusing on three different eras: 1) the pre-ATRA era; 2) the ATRA era; 3) the ATO era.

EXPERT OPINION

The combination of ATRA and ATO is effective and curative for the majority of APL patients. It has been approved for low/intermediate risk cases while an experimental trial with a minimal addition of chemotherapy for high-risk ones is ongoing. Disease relapse is infrequent and can be cured with ATRA-ATO rechallenging, with or without subsequent transplantation depending on the interval between complete remission and relapse. New therapeutic landscapes contemplate the use of an oral chemo-free ATRA-ATO combination, implementing treatment as outpatient care, thus increasing quality of life and decreasing medical costs.

Differential Survival Outcomes Between De Novo and Secondary Acute Promyelocytic Leukemia: An Updated Population-based study

BACKGROUND

Whether the characteristics and outcome of secondary acute promyelocytic leukemia (s-APL) are similar to de no APL (dn-APL) remains unknown.

PATIENTS AND METHODS

Using the SEER database, we identified 3877 patients with APL diagnosed from 2000 to 2014, including 465 s-APL and 3412 dn-APL.

RESULTS

Compared with dn-APL, s-APL werecharacterized by older median age, and a higher early mortality rate. Multivariate Cox model showed s-APL, older age, earlier year of diagnosis, and male gender were independently associated with worse survival. Notably, s-APL had a significantly inferior survival regardless of gender, race, marital status, and year of diagnosis. However, the difference between the 2 cohorts was only evident in younger patients (≤ 65 years) but was lost in older patients (> 65 years). Additionally, the majority of index cancer type was breast and prostate in female and male s-APL, respectively. Latency < 3 years was associated with superior survival in s-APL with breast index cancer.

CONCLUSIONS

Inferior survival of s-APL points to the need for treatment improvement.

Acute promyelocytic leukemia current treatment algorithms

In 1957, Hillestad et al. defined acute promyelocytic leukemia (APL) for the first time in the literature as a distinct type of acute myeloid leukemia (AML) with a “rapid downhill course” characterized with a severe bleeding tendency. APL, accounting for 10–15% of the newly diagnosed AML cases, results from a balanced translocation, t(15;17) (q22;q12-21), which leads to the fusion of the promyelocytic leukemia (PML) gene with the retinoic acid receptor alpha (RARA) gene. The PML–RARA fusion oncoprotein induces leukemia by blocking normal myeloid differentiation. Before using anthracyclines in APL therapy in 1973, no effective treatment was available. In the mid-1980s, all-trans retinoic acid (ATRA) monotherapy was used with high response rates, but response durations were short. Later, the development of ATRA, chemotherapy, and arsenic trioxide combinations turned APL into a highly curable malignancy. In this review, we summarize the evolution of APL therapy, focusing on key milestones that led to the standard-of-care APL therapy available today and discuss treatment algorithms and management tips to minimize induction mortality.

Evaluation of arsenic species in leukocytes and granulocytes of acute promyelocytic leukemia patients treated with arsenic trioxide

Concentrations of arsenic metabolites were important to clarify the sensitivity and resistance of APL (acute promyelocytic leukemia) patients to arsenic trioxide (As₂O₃). Our purpose was to evaluate levels and distributions of arsenic species in leukocytes and granulocytes of APL patients. Inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were measured by high performance liquid chromatography coupled inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Leukocytes were collected from 21 patients treated with As₂O₃ during induction, consolidation, and drug-withdrawal period. The upregulation of granulocytes in induction period was closely related to the differentiation of promyelocytes. Therefore, granulocytes were collected during induction period from 4 APL patients and purified by flow cytometry sorting using a panel of monoclonal antibodies specific for CD45, CD3, CD14, and CD19. The developed HPLC-ICP-MS method was precise and accurate with the limit of quantification of 0.5 ng/mL. During induction, consolidation, and drug-withdrawal period, the general trend of arsenic species was iAs > MMA > DMA (P < 0.05) in leukocytes. iAs was predominant arsenic species with median concentration of 10.84 (6.03-14.62) ng/mL. MMA was major methylated metabolite with median concentration of 0.94 (0.60-2.50) ng/mL. Moreover, arsenicals were detected in leukocytes during drug-withdrawal. In granulocytes, iAs was found during induction period with median concentration of 1.08 ng/mL, while MMA and DMA were not detected. These results showed that iAs was the primary arsenic species in leukocytes and granulocytes from APL patients treated with As₂O₃. This study suggested that iAs might play a dominant therapeutic role during the whole treatment process of APL.

Mutational profile of ZBTB16-RARA-positive acute myeloid leukemia

Background

The ZBTB16‐RARA fusion gene, resulting from the reciprocal translocation between ZBTB16 on chromosome 11 and RARA genes on chromosome 17 [t(11;17)(q23;q21)], is rarely observed in acute myeloid leukemia (AML), and accounts for about 1% of retinoic acid receptor‐α (RARA) rearrangements. AML with this rare translocation shows unusual bone marrow (BM) morphology, with intermediate aspects between acute promyelocytic leukemia (APL) and AML with maturation. Patients may have a high incidence of disseminated intravascular coagulation at diagnosis, are poorly responsive to all‐trans retinoic acid (ATRA) and arsenic tryoxyde, and are reported to have an overall poor prognosis.

Aims

The mutational profile of ZBTB16‐RARA rearranged AML has not been described so far.

Materials and methods

We performed targeted next‐generation sequencing of 24 myeloid genes in BM diagnostic samples from seven ZBTB16‐RARA+AML, 103 non‐RARA rearranged AML, and 46 APL. The seven ZBTB16‐RARA‐positive patients were then screened for additional mutations using whole exome sequencing (n = 3) or an extended cancer panel including 409 genes (n = 4).

Results

ZBTB16‐RARA+AML showed an intermediate number of mutations per patient and involvement of different genes, as compared to APL and other AMLs. In particular, we found a high incidence of ARID1A mutations in ZBTB16‐RARA+AML (five of seven cases, 71%). Mutations in ARID2 and SMARCA4, other tumor suppressor genes also belonging to SWI/SNF chromatin remodeling complexes, were also identified in one case (14%).

Discussion and conclusion

Our data suggest the association of mutations of the ARID1A gene and of the other members of the SWI/SNF chromatin remodeling complexes with ZBTB16‐RARA+AMLs, where they may support the peculiar disease phenotype.

Arsenic compounds: The wide application and mechanisms applied in acute promyelocytic leukemia and carcinogenic toxicology

Arsenic (As), as well as its various compounds have been widely used for nearly 4000 years either as drugs or poisons. These compounds are valuable in the treatment of various diseases ranging from dermatosis to cancer, thereby emphasizing their important roles as therapeutic agents. The ability of As compounds, especially arsenic trioxide (ATO) in the treatment of acute promyelocytic leukemia (APL), has fundamentally altered people's understanding of the poison, and has become a major factor in the re-emergence of Western medicine candidates to treat leukemia and other solid tumors. However, long-term exposure to As has been correlated with numerous disadvantageous influences on health, particularly carcinogenesis. Importantly, accumulating evidence suggests that biotransformation of As, as a step to eliminate As from the human body, can induce alterations at the genetic and epigenetic levels, resulting in therapeutic effects or carcinogenesis. In this article, we aimed to provide a systematic overview of the primary contributions associated with As and its compounds, as well as the detailed mechanisms applied in APL cells and carcinogenic toxicology. This review may help to understand the underlying mechanisms and safe wide clinical applications of medicinal As along with its compounds.

NeuroD1 Dictates Tumor Cell Differentiation in Medulloblastoma

Tumor cells are characterized by unlimited proliferation and perturbed differentiation. Using single-cell RNA sequencing, we demonstrate that tumor cells in medulloblastoma (MB) retain their capacity to differentiate in a similar way as their normal originating cells, cerebellar granule neuron precursors. Once they differentiate, MB cells permanently lose their proliferative capacity and tumorigenic potential. Differentiated MB cells highly express NeuroD1, a helix-loop-helix transcription factor, and forced expression of NeuroD1 promotes the differentiation of MB cells. The expression of NeuroD1 in bulk MB cells is repressed by trimethylation of histone 3 lysine-27 (H3K27me3). Inhibition of the histone lysine methyltransferase EZH2 prevents H3K27 trimethylation, resulting in increased NeuroD1 expression and enhanced differentiation in MB cells, which consequently reduces tumor growth. These studies reveal the mechanisms underlying MB cell differentiation and provide rationales to treat MB (potentially other malignancies) by stimulating tumor cell differentiation.

Cheng et al. demonstrate that medulloblastoma cells retain the capacity to undergo differentiation. The differentiation of tumor cells is regulated by NeuroD1 expression, which is repressed by H3K27me3 in tumor cells. EZH2 inhibitors suppress medulloblastoma growth by stimulating tumor cell differentiation.

CUDC-101 overcomes arsenic trioxide resistance via caspase-dependent promyelocytic leukemia-retinoic acid receptor alpha degradation in acute promyelocytic leukemia

Although arsenic trioxide (ATO) treatment has transformed acute promyelocytic leukemia (APL) from the most fatal to the most curable hematological cancer, many high-risk APL patients who fail to achieve a complete molecular remission or relapse become resistant to ATO. Herein, we report that 7-(4-(3-ethynylphenylamino)-7-methoxyquinazolin-6-yloxy)-N-hydroxyheptanamide (CUDC-101) exhibits specific anticancer effects on APL and ATO-resistant APL in vitro and in vivo, while showing negligible cytotoxic effect on the noncancerous cells including normal CD34 cells and bone marrow mesenchymal stem cells from APL patients. Further mechanistic studies show that CUDC-101 triggers caspase-dependent degradation of the promyelocytic leukemia-retinoic acid receptor alpha fusion protein. As a result, APL and ATO-resistant APL cells undergo apoptosis upon CUDC-101 treatment and this apoptosis-inducing effect is even stronger than that of ATO. Finally, using a xenograft mouse model, we demonstrated that CUDC-101 significantly represses leukemia development in vivo. In conclusion, these results suggested that CUDC-101 can serve as a potential candidate drug for APL, particularly for ATO-resistant APL.

Tetraploid acute promyelocytic leukemia with double translocation t (15,17) PML/RARA: the first case report in Croatia and Europe

Acute promyelocytic leukemia (APL) is characterized by the translocation t (15;17)(q22;q21) cytogenetic abnormality in the majority of cases. In most of the cases the cells of APL have normal, diploid karyotype. There are very few cases presented with very rare tetraploid karyotype with double translocation t(15;17)(q22;q12). We report the first case of tetraploid APL with double translocation t(15, 17) in Europe. A 66-year old male patient presented with dyspnea and unexplained dental bleeding. Blood work showed a white blood cell count of 1x109/L, hemoglobin was 124 g/ L, platelet count was 61x109/L and fibrinogen level was low (1.4 g/L). Cytogenetics showed a tetraploid karyotype. Fluorescence in situ hybridization analysis proved existence of clonal cells with translocation t (15,17) in 15% of metaphase nuclei and tetraploid subclonal cells with the same translocation in 70% of metaphase nuclei. Findings were consistent with APL, tetraploid variant and the patient started all-trans retinoic acid (ATRA) treatment. The patient achieved complete remission in 2 months and completed three consolidation therapy cycles with ATRA, idarubicin or mitraxontrate. Currently, the patient is undergoing maintenance therapy with ATRA, 6-mercaptopurine and weekly methotrexate.

Differentiation therapy of myeloid leukemia: four decades of development

Acute myeloid leukemia is characterized by arrested differentiation, and agents that overcome this block are therapeutically useful, as shown by the efficacy of all-trans retinoic acid in acute promyelocytic leukemia. However, the early promise of differentiation therapy did not translate into clinical benefit for other subtypes of acute myeloid leukemia, in which cytotoxic chemotherapeutic regimens remained the standard of care. Recent advances, including insights from sequencing of acute myeloid leukemia genomes, have led to the development of targeted therapies, comprising agents that induce differentiation of leukemic cells in preclinical models and clinical trials, thus rejuvenating interest in differentiation therapy. These agents act on various cellular processes including dysregulated metabolic programs, signaling pathways, epigenetic machinery and the cell cycle. In particular, inhibitors of mutant IDH1/2 and FLT3 have shown clinical benefit, leading to approval by regulatory bodies of their use. Besides the focus on recently approved differentiation therapies, this review also provides an overview of differentiation- inducing agents being tested in clinical trials or investigated in preclinical research. Combinatorial strategies are currently being tested for several agents (inhibitors of KDM1A, DOT1L, BET proteins, histone deacetylases), which were not effective in clinical studies as single agents, despite encouraging anti-leukemic activity observed in preclinical models. Overall, recently approved drugs and new investigational agents being developed highlight the merits of differentiation therapy; and ongoing studies promise further advances in the treatment of acute myeloid leukemia in the near future.

RNA Targeting in Acute Myeloid Leukemia

Nucleosides and their analogues constitute an essential family of anticancer drugs. DNA has been the presumptive target of the front-line prodrug for acute myeloid leukemia (AML), cytarabine (ara-C), since the 1980s. Here, the biomolecular targeting of ara-C was evaluated in primary white blood cells using the ara-C mimic "AzC" and azide-alkyne "click" reactions. Fluorescent staining and microscopy revealed that metabolic incorporation of AzC into primary white blood cells was unexpectedly enhanced by the DNA polymerase inhibitor aphidicholine. According to RNaseH digestion and pull-down-and-release experiments, AzC was incorporated into short RNA fragments bound to DNA in peripheral blood monocytes (PBMCs) collected from all six healthy human donors tested. Samples from 22 AML patients (French-American-British classes M4 and M5) exhibited much more heterogeneity, with 27% incorporating AzC into RNA and 55% into DNA. The overall survival of AML patients whose samples incorporated AzC into RNA was approximately 3-fold higher as compared to that of the DNA cohort (p ≤ 0.056, χ² = 3.65). These results suggest that the RNA primers of DNA synthesis are clinically favorable targets of ara-C, and that variable incorporation of nucleoside drugs into DNA versus RNA may enable future patient stratification into treatment-specific subgroups.

Second Primary Malignancy after Acute Promyelocytic Leukemia: A Population-Based Study

Simple Summary

Acute promyelocytic leukemia (APL) is a rare and aggressive subtype of acute myeloid leukemia (AML). Since the introduction of all-trans-retinoic acid (ATRA) in APL management, the survival rate has increased substantially. However, there is evidence that retinoids might enhance tumor growth and the risk of secondary malignancies. The relationship between secondary cancer risk and APL treatment that includes ATRA is incompletely characterized. In this study, we investigated the risk factors associated with second primary malignancies after treatment of APL. Age ≥ 40 years at diagnosis of APL was significantly associated with an increased risk of second malignancies. Our findings suggest a potential carcinogenic role for ATRA in the salivary gland, liver, and soft tissue malignancies. Moreover, secondary tumors were significantly more frequent among patients with primary APL than in individuals with non-APL malignancies. Our finding suggests opportunities for surveillance for patients who completed treatment for APL.

Abstract

Acute promyelocytic leukemia (APL), is now highly curable with treatment approaches that include all-trans retinoic acid (ATRA). The high incidence of APL in the Hispanics suggests an association with genetic variants in this population. Information on second primary malignancies (SPMs) in patients with APL is limited. The Surveillance, Epidemiology, and End Results (SEER) database was used to interrogate whether the rate of SPMs in patients with APL was associated with ethnicity and/or ATRA treatment. Between 2000 and 2016, 116 cases of SPM were diagnosed among 4019 patients with APL. The mean age at diagnosis of primary APL was 53.9 years (±15.7 years), and the mean age at diagnosis of SPMs was 59.0 years (±14.5 years). Comparisons with 3774 APL survivors who did not develop SPMs revealed that age ≥40 years at diagnosis of APL (p < 0.001) and non-Hispanic white ethnicity (p = 0.025) were associated with SPMs in APL survivors. Salivary gland, liver, and soft tissue malignancies were significantly more common in patients with primary APL than in individuals with non-APL malignancies. A risk analysis comparing patients who had APL with patients who had non-APL AML suggests that SPMs after APL is associated with ATRA treatment. Therefore, patient follow-up after APL should focus on early diagnosis of SPMs.

Development and validation of a droplet digital PCR assay for the evaluation of PML-RARα fusion transcripts in acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is an aggressive disease that requires prompt treatment. Promyelocytic leukemia protein-retinoic acid receptor α (PML-RARα) fusion genes resulting from reciprocal translocation are considered a molecular basis for diagnosing APL. Moreover, PML-RARα fusion gene testing is an essential tool for monitoring the response to therapy via minimal residual disease and providing a diagnosis before rapid disease progression in APL. The present study developed a novel droplet digital PCR (ddPCR) assay to rapidly detect two PML-RARα variants (bcr1 and bcr3) and compared its limit of detection (LOD) with quantitative PCR (qPCR). It was demonstrated that the LOD of ddPCR for PML-RARα reached 0.001%, and the evaluation of high copy number samples of PML-RARα by ddPCR correlated well with qPCR. Furthermore, clinical sample testing with ddPCR found that 34 and 24% samples were bcr-1-positive and bcr3-positive, respectively. However, according to qPCR, 30% of the samples were bcr1-positive and 20% were bcr3-positive. In addition, the concordance rate between ddPCR and qPCR reaction was 86%. While monitoring minimal residual disease, the PML-RARα mutation rate of three patients who recovered well decreased to 0.34%. However, one patient who was bcr3-positive and relapsed had a mutation rate of 13% while in remission, indicating that the bcr3 isoform may be an adverse prognostic factor affecting recovery. Therefore, the present results suggested that this novel ddPCR assay may be useful for monitoring and evaluating the treatment effects and prognosis of APL.

Arsenic trioxide enhances the chemotherapeutic efficiency of cisplatin in cholangiocarcinoma cells via inhibiting the 14-3-3ε-mediated survival mechanism

Cholangiocarcinoma (CCA) is the second most frequent primary liver carcinoma with high degrees of malignancy and mortality. Chemotherapy plays a key role in the treatment of CCA, however, the low chemotherapeutic efficiency leads to a bottleneck. So unraveling the potential mechanisms to enhance the efficiency (reduced the dosage and enhanced the effects of chemotherapy drugs) and identifying alternative therapeutic strategies in CCA are urgently needed. Here, we found that, in CCA cells, when cisplatin (CDDP) displayed anti-tumor effects, it activated 14-3-3ε simultaneously, which in turn formed a survival mechanism via the phosphorylation of phosphatidylinositol 3-kinase/protein kinase B (PI-3K/Akt). However, low concentrations of arsenic trioxide (ATO) could disrupt such survival mechanism and enhanced the efficiency. For the molecular mechanisms, ATO attenuated 14-3-3ε at both transcriptional and post-transcriptional (ubiquitination degradation) levels. Such repressive effect blocked the activation of PI-3K/Akt, and its downstream anti-apoptotic factors, B-cell lymphoma 2 (Bcl-2), and survivin. Collectively, our present study revealed that the synergistic effects of ATO and CDDP could be a novel approach for enhancing the efficiency, which provides an innovative therapeutic vision for the treatment of CCA.

Current strategies for detection and approach to measurable residual disease in acute myeloid leukemia

Baseline cytogenetic/genetic features have been widely recognized to play a critical prognostic role in acute myeloid leukemia (AML) and have proven useful in designing risk-adapted treatment strategies. Nevertheless, to improve further the outcome of AML patients we are still in need of accurate methods to explore the quality of response and to adequately discriminate patients who are likely to relapse over time from those who are in deep and stable remission. In this view, is it well established that measurement of leukemic cells surviving chemotherapy (called measurable residual disease, MRD) during the course of treatment may be a reliable biomarker in predicting relapse. Detection of MRD relies on highly sensitive techniques, such as quantitative polymerase chain reaction and multiparametric flow cytometry, which, due to their levels of specificity and sensitivity, are increasingly included in the decision-making process of AML treatment. In the present manuscript, we will review the current techniques of MRD investigation and their clinical contribution to AML management.

Clinical and molecular consequences of fusion genes in myeloid malignancies

Leukemias are heterogeneous diseases characterized by aberrant hematopoietic stem and progenitor cells (HSPCs). Oncogenic fusion genes and proteins, produced via gross chromosomal rearrangements, such as chromosomal translocation, insertion, and inversion, play important roles in hematologic malignancies. These oncoproteins alter fundamental cellular properties, such as self-renewal, differentiation, and proliferation, and confer leukemogenic potential to HSPCs. In addition to providing fundamental insights into the process of leukemic transformation, these fusion genes provide targets for treatment and monitoring of myeloid leukemias. Furthermore, new technologies such as next-generation sequencing have allowed additional insights into the nature of leukemic fusion genes. In this review, we discuss the history, biologic effect, and clinical impact of fusion genes in the field of myeloid leukemias.

DDX5-targeting fully human monoclonal autoantibody inhibits proliferation and promotes differentiation of acute promyelocytic leukemia cells by increasing ROS production

Acute promyelocytic leukemia (APL) therapy involves the compounds cytotoxic to both malignant tumor and normal cells. Relapsed APL is resistant to subsequent chemotherapy. Novel agents are in need to kill APL cells selectively with minimal toxicity. DDX5 has been recognized to be a novel target to suppress acute myeloid leukemia (AML). However, the role of DDX5 remains elusive in APL. Here a DDX5-targeting fully human monoclonal autoantibody named after 2F5 was prepared. It is demonstrated that 2F5 selectively inhibited APL cell proliferation without toxicity to normal neutrophil and tissues. Moreover, 2F5 was confirmed to induce G0/G1 phase arrest in APL cells, and promote APL cell differentiation combined with decreased DDX5 expression and increased reactive oxygen species (ROS) production. Knockdown of DDX5 by siRNA also inhibited proliferation, promoted cell differentiation and enhanced ROS production in APL cells. However, the ROS inhibitor reversed the effects of 2F5 on DDX5 and ROS in APL cells. Thus, we conclude that DDX5-targeting 2F5 inhibits APL cell proliferation, and promotes cell differentiation via induction of ROS. 2F5 showed the therapeutic value of fully human monoclonal autoantibody in APL, which provides a novel and valid approach for treatment of relapse/refractory APL.

Case report: An unusual presentation of acute promyelocytic leukemia in a middle aged female mimicking dengue infection

RATIONALE

Acute promyelocytic leukemia (APL) is an uncommon subtype of acute myeloid leukemia (AML). M3v phenotype is a less common presentation of APL and these patients usually present with leukocytosis and abnormal promyelocytes that are characterized by sparse granulation and are less likely to have faggot cells with multiple Auer rods. Distinguishing M3v phenotype from acute febrile illness can be challenging as the diagnosis relies on examination of peripheral smear.

PATIENT CONCERNS

Fifty-seven-year-old female who presented after recent trip to Dominican Republic for high grade fever and gum bleeding. She was exposed to patients with Dengue fever during her stay. At presentation, patient had leukocytosis, thrombocytopenia, and urinalysis showing bacteria and white cell. She was started on treatment for urinary tract infection. Patient remained febrile and thrombocytopenia worsened. On day 2, flow cytometry of the peripheral smear showed 43% medium sized blasts. Fluorescence in situ hybridization was positive for promyelocytic leukemia/retinoic acid receptor alpha.

DIAGNOSES

The patient was diagnosed with APL.

INTERVENTIONS

Patient was started on treatment with all-trans retinoic acid and arsenic trioxide along with supportive care OUTCOMES:: Patient had a favorable clinical response and her symptoms subsided.

LESSONS

Flow cytometry of the peripheral smear is key to diagnosis of suspected APL. One must maintain high suspicion for this life-threatening condition as early diagnosis saves lives.

Detection and management of acute myeloid leukemia measurable residual disease: is it standard of care?

PURPOSE OF REVIEW

In the present manuscript, we will review the current approaches to investigate measurable residual disease (MRD) and its clinical applications in AML management.

RECENT FINDINGS

Over the last decades, several methods have been developed to trace MRD, with flow cytometry and polymerase chain reaction (PCR) being the most reliable. However, new technologies, such as digital PCR and Next-Generation Sequencing are emerging as particularly useful in AML. The 2017 European LeukemiaNet (ELN) recommendations have incorporated MRD assessment to define the response criteria to therapy, and more recently, the ELN MRD Working Party has published guidelines for the use of MRD in clinical practice.

SUMMARY

Morphologic complete remission (mCR) after induction therapy, has been consistently shown not only to have a critical prognostic role but also to fail in predicting relapse on an individual basis. Major attempts to improve our prediction capability have been made by measuring the residual levels of leukemic cells that persist in the bone marrow after chemotherapy. This number of cells, also called MRD, harbors in the bone marrow below the threshold of morphology and is responsible for leukemia recurrence. Therefore, the detection of MRD promises to help predict the risk of relapse, allowing a more proper patients' risk-stratification and the use of risk-tailored therapeutic strategy.

miRNA-98-5p Targeting IGF2BP1 Induces Mesenchymal Stem Cell Apoptosis by Modulating PI3K/Akt and p53 in Immune Thrombocytopenia

Immune thrombocytopenia (ITP) is a common hematological autoimmune disease, in which defective mesenchymal stem cells (MSCs) are potentially involved. Our previous study suggested that MSCs in ITP patients displayed enhanced apoptosis. MicroRNAs (miRNAs) play important roles in ITP by affecting megakaryopoiesis, platelet production and immunoregulation, whereas the roles of miRNAs in ITP-MSCs remain unknown. In a previous study, we performed microarray analysis to obtain mRNA and miRNA profiles of ITP-MSCs. In the present study, we reanalyze the data and identify miR-98-5p as a candidate miRNA contributing to MSC deficiency in ITP. miR-98-5p acts through targeting insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), and the subsequent downregulation of insulin-like growth factor 2 (IGF-2) causes inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, which is involved in the process of MSC deficiency. Furthermore, miR-98-5p upregulates p53 by inhibiting β-transducin repeat-containing protein (β-TrCP)-dependent p53 ubiquitination. Moreover, miR-98-5p overexpression impairs the therapeutic effect of MSCs in ITP mice. All-trans retinoic acid (ATRA) protects MSCs from apoptosis by downregulating miR-98-5p, thus providing a potential therapeutic approach for ITP. Our findings demonstrate that miR-98-5p is a critical regulator of ITP-MSCs, which will help us thoroughly understand the pathogenesis of ITP.

Improved Outcomes of All-trans-retinoic Acid and Arsenic Trioxide Plus Idarubicin as a Frontline Treatment in Adult Patients With Acute Promyelocytic Leukemia

INTRODUCTION

The purpose of this study was to explore the outcomes of all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) plus idarubicin (IDA) as a frontline treatment in adult patients with acute promyelocytic leukemia (APL).

PATIENTS AND METHODS

We analyzed the outcomes of ATRA and intravenous ATO plus IDA as a frontline induction therapy in 118 patients with APL with high-risk (HR) and standard-risk (SR) disease from January 2008 to December 2017. The medical records of 118 patients with APL (HR, n = 45; SR, n = 73) who received the frontline triple combination regimen at Henan Provincial People's Hospital and Tongji Hospital were retrospectively reviewed. Consolidation therapy comprised 6 cycles of ATO and ATRA plus IDA, and IDA was administered in 1 to 4 cycles of consolidation therapy based on the comparable clinical efficacy compared with 6 cycles and fewer side effects to myocardium without subsequent maintenance therapy.

RESULTS

Of 118 patients, there were 3 (2.5%) early deaths and 115 (97.5%) hematologic complete remissions; 102 (88.7%) of 115 patients achieved molecular complete remission following induction therapy, and all patients were polymerase chain reaction-negative for promyelocytic leukemia-retinoic acid receptor alpha after the first cycle of consolidation therapy. The 5-year overall survival (OS) and event-free survival (EFS) were 93.0% ± 2.9% and 92.4% ± 3.0%, respectively. Early death, hematologic complete remissions, molecular complete remissions, and toxicities were comparable between the HR and SR groups. The cumulative incidence of relapse in the HR group was 4.7% (n = 2), and the cumulative incidence of relapse in the SR group was 0. The OS and EFS of the SR and HR groups were comparable (92.3% ± 4.5% vs. 92.8% ± 4.0%; X² = 0.263; P = .608; 92.3% ± 4.5% vs. 91.1% ± 4.2%, X² = 0.917; P = .338). The total dosage of IDA was approximately 181 to 258 mg, and no patient experienced cardiotoxicity. OS and EFS were not influenced by fms-related tyrosine kinase 3 internal tandem duplication mutation status (P = .405 and P = .528, respectively).

CONCLUSION

The triple combination of ATRA and ATO plus IDA as both an induction and consolidation therapy for the HR and SR groups attained excellent outcomes, and this regimen was effective, safe, and easy, without maintenance therapy. The triple combination treatment might be a preferred frontline therapy for patients with APL, especially for those with HR or the APL fms-related tyrosine kinase 3 internal tandem duplication mutation.

Anti-PD-L1-modified and ATRA-loaded nanoparticles for immuno-treatment of oral dysplasia and oral squamous cell carcinoma

Aim: To develop nanomedicines for immuno-therapy of oral dysplasia and oral squamous cell carcinoma. Materials & methods: All-trans retinoic acid (ATRA)-poly(lactide-co-glycolide acid) (PLGA)-poly(ethylene glycol) (PEG)-programmed death-ligand 1 (PD-L1) nanomedicines were fabricated by loading ATRA into PLGA-PEG nanocarriers and modification using an anti-PD-L1 antibody. Results: ATRA-PLGA-PEG-PD-L1 nanoparticles showed fast cellular uptake, significantly inhibited proliferation and induced apoptosis in DOK and CAL27 cells. Moreover, in C3H tumor-bearing mice, ATRA-PLGA-PEG-PD-L1 nanoparticles more specifically targeted tumor cells, enhanced anticancer activity and reduced side effects when compared with free ATRA. Furthermore, CD8+ T cells were activated around PD-L1 positive cells in the tumor microenvironment after treatment. Conclusion: ATRA-PLGA-PEG-PD-L1 nanoparticles had low toxicity, high biocompatibility and specifically targeted oral dysplasia and squamous carcinoma cells both in vitro and in vivo.

Acute promyelocytic leukemia (APL): a review of the literature

Acute Promyelocytic Leukemia (APL) is characterized by a block in differentiation where leukemic cells are halted at the promyelocyte stage. A characteristic balanced chromosomal translocation between chromosomes 15 and 17 t (15;17) (q24; q21) is seen in 95% of cases — the translocation results in the formation of the PML-RARA fusion protein. The introduction of retinoic acid (RA) and arsenic trioxide (ATO) has been responsible for initially remarkable cure rates. However, relapsed APL, particularly in the high-risk subset of patients, remains an important clinical problem. In addition, despite the success of ATRA & ATO, many clinicians still elect to use cytotoxic chemotherapy in the treatment of APL. Patients who become resistant to ATO have an increased risk of mortality. The probability of relapse is significantly higher in the high-risk subset of patients undergoing treatment for APL; overall approximately 10-20% of APL patients relapse regardless of their risk stratification. Furthermore, 20-25% of patients undergoing treatment will develop differentiation syndrome, a common side effect of differentiation agents. Recent evidence using in vitro models has shown that mutations in the B2 domain of the PML protein, mediate arsenic resistance. Alternative agents and approaches considering these clinical outcomes are needed to address ATO resistance as well as the relapse rate in high risk APL.

Old dog, new trick: Trivalent arsenic as an immunomodulatory drug

Trivalent arsenic (As(III)) is recently found to be an immunomodulatory agent. As(III) has therapeutic potential in several autoimmune and inflammatory diseases in vivo. In vitro, it selectively induces apoptosis of immune cells due to different sensitivity. At a non-toxic level, As(III) shows its multifaceted nature by inducing either pro- or anti-inflammatory functions of immune subsets. These effects are exerted by either As(III)-protein interactions or as a consequence of As(III)-induced homeostasis imbalance. The immunomodulatory properties also show synergistic effects of As(III) with cancer immunotherapy. In this review, we summarize the immunomodulatory effects of As(III), focusing on the effects of As(III) on immune subsets in vitro, on mouse models of immune-related diseases, and the role of As(III) in cancer immunotherapy. Updates of the mechanisms of action, the pioneer clinical trials, dosing, and adverse events of therapeutic As(III) are also provided.

Is There Still a Role for Autologous Stem Cell Transplantation for the Treatment of Acute Myeloid Leukemia?

After intensive induction chemotherapy and complete remission achievement, patients with acute myeloid leukemia (AML) are candidates to receive either high-dose cytarabine-based regimens, or autologous (ASCT) or allogeneic (allo-SCT) hematopoietic stem cell transplantations as consolidation treatment. Pretreatment risk classification represents a determinant key of type and intensity of post-remission therapy. Current evidence indicates that allo-SCT represents the treatment of choice for high and intermediate risk patients if clinically eligible, and its use is favored by increasing availability of unrelated or haploidentical donors. On the contrary, the adoption of ASCT is progressively declining, although numerous studies indicate that in favorable risk AML the relapse rate is lower after ASCT than chemotherapy. In addition, the burden of supportive therapy and hospitalization favors ASCT. In this review, we summarize current indications (if any) to ASCT on the basis of molecular genetics at diagnosis and minimal residual disease evaluation after induction/consolidation phase. Finally, we critically discuss the role of ASCT in older patients with AML and acute promyelocytic leukemia.

Incidence of acute promyelocytic leukemia across Europe: results of RARECAREnet-a population-based study

The scarcity of studies performed over the past decades in Central and South America provided clues that the prevalence of acute promyelocytic leukemia (APL)-a rare and distinct subtype of acute myeloid leukemia-might be higher among descendants of Spaniards, as compared to other ethnic groups. Currently, a comprehensive apprehension on APL incidence across Europe has yet been established. Therefore, we conducted a population-based study to assess the incidence of APL across Europe. We selected all patients diagnosed with APL in Europe from the RARECAREnet database that holds data from 94 cancer registries across 27 European countries on rare malignancies diagnosed during 2000-2007. Age-standardized incidence rates (ASRs) with 95% confidence intervals (CIs) were calculated for the European pool per 100,000 person-years. Also, crude incidence rates with 95% CIs were calculated per 100,000 person-years by country. Overall, 1,876 patients with APL (48% male and 24% aged ≥65 years) were included in our analytic cohort. The overall ASR of APL was 0.112 (95% CI, 0.107-0.117) in Europe. The incidence of APL varied considerably across Europe, with the highest incidence in Spain (0.257; 95% CI, 0.205-0.317), as compared to the European average. Altogether, these finding adds additional support to the hypothesis that APL might be more prevalent among individuals with Spanish ancestry. Future research is warranted to specifically explore etiologic factors of APL across different genetic and environmental backgrounds.

Targeting Angiogenesis by Blocking the ATM-SerRS-VEGFA Pathway for UV-Induced Skin Photodamage and Melanoma Growth

Retinoic acid (RA) has been widely used to protect skin from photo damage and skin carcinomas caused by solar ultraviolet (UV) irradiation, yet the mechanism remains elusive. Here, we report that all-trans retinoic acid (tRA) can directly induce the expression of a newly identified potent anti-angiogenic factor, seryl tRNA synthetase (SerRS), whose angiostatic role can, however, be inhibited by UV-activated ataxia telangiectasia mutated (ATM) kinase. In both a human epidermal cell line, HaCaT, and a mouse melanoma B16F10 cell line, we found that tRA could activate SerRS transcription through binding with the SerRS promoter. However, UV irradiation induced activation of ATM-phosphorylated SerRS, leading to the inactivation of SerRS as a transcriptional repressor of vascular endothelial growth factor A (VEGFA), which dampened the effect of tRA. When combined with ATM inhibitor KU-55933, tRA showed a greatly enhanced efficiency in inhibiting VEGFA expression and a much better protection of mouse skin from photo damage. Also, we found the combination greatly inhibited tumor angiogenesis and growth in mouse melanoma xenograft in vivo. Taken together, tRA combined with an ATM inhibitor can greatly enhance the anti-angiogenic activity of SerRS under UV irradiation and could be a better strategy in protecting skin from angiogenesis-associated skin damage and melanoma caused by UV radiation.

Beyond Cisplatin: Combination Therapy with Arsenic Trioxide

Platinum drugs (cisplatin, oxaliplatin, and carboplatin) and arsenic trioxide are the only commercial inorganic non-radioactive anticancer drugs approved by the US Food and Drug Administration. Numerous efforts are underway to take advantage of the synergy between the anticancer activity of cisplatin and arsenic trioxide - two drugs with strikingly different mechanisms of action. These include co-encapsulation of the two drugs in novel nanoscale delivery systems as well as the development of small molecule agents that combine the activity of these two inorganic materials. Several of these new molecular entities containing Pt-As bonds have broad anticancer activity, are robust in physiological buffer solutions, and form stable complexes with biopolymers. This review summarizes results from a number of preclinical studies involving the combination of cisplatin and As2O3, co-encapsulation and nanoformulation efforts, and the chemistry and cytotoxicity of the first member of platinum anticancer agents with an arsenous acid moiety bound to the platinum(II) center: arsenoplatins.

Mutational landscape of patients with acute promyelocytic leukemia at diagnosis and relapse

Despite the high probability of cure of patients with acute promyelocytic leukemia (APL), mechanisms of relapse are still largely unclear. Mutational profiling at diagnosis and/or relapse may help to identify APL patients needing frequent molecular monitoring and early treatment intervention. Using an NGS approach including a 31 myeloid gene-panel, we tested BM samples of 44 APLs at the time of diagnosis, and of 31 at relapse. Mutations in PML and RARA genes were studied using a customized-NGS-RNA panel. Patients relapsing after ATRA-chemotherapy rarely had additional mutations (P = .009). In patients relapsing after ATRA/ATO, the PML gene was a preferential mutation target. We then evaluated the predictive value of mutations at APL diagnosis. A median of two mutations was detectable in 9/11 patients who later relapsed, vs one mutation in 21/33 patients who remained in CCR (P = .0032). This corresponded to a significantly lower risk of relapse in patients with one or less mutations (HR 0.046; 95% CI 0.011-0.197; P < .0001). NGS-analysis at the time of APL diagnosis may inform treatment decisions, including alternative treatments for cases with an unfavorable mutation profile.